title: Time for a paradigm shift with computerized adaptive testing of general physical function outcomes measurements.
abstract: BACKGROUND
  Patient-reported outcomes (PRO) are critical to understanding the value of orthopedic treatments. We hypothesized that use of the computerized adaptive testing from a well-characterized physical function item bank would show superiority in assessing all levels of physical function compared to current standard generic physical function outcomes instruments for foot and ankle patients.
  
  
  METHODS
  In a population of 126 foot and ankle patients we compared the psychometric properties for three PROs: the Physical Function subscale of the Medical Outcomes General Health Survey (SF-36 PF) version 2, the Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function (PF) Computerized Adaptive Test (CAT), and the Lower Extremity (LE) CAT. A Rasch item response theory (IRT) model was applied to assess and compare the fit, dimensionality, reliability, validity, and coverage.
  
  
  RESULTS
  The unexplained variance for the PF CAT was 3.9% and the LE CAT was 2.1%, suggesting each instrument explained a single concept. The SF-36 PF had more concerning unexplained variance of 7.6%. We found no floor or ceiling effects for the PF CAT, a minimal floor effect (1.6%) but no ceiling effect for the LE CAT, and an 11.1% floor effect and 9.5% ceiling effect for the SF-36 PF.
  
  
  CONCLUSIONS
  Foot and ankle clinicians and researchers interested in measuring patient perceived functional outcomes with a generic instrument should consider using either the PF CAT or the LE CAT rather than the SF-36 PF. Further studies comparing these CATs to anatomic specific instruments are needed.
  
  
  METHODS
  Level I, diagnostic study.
authors.affiliation: University of Utah School of Medicine, Salt Lake City, UT, USA.
authors.forename: Man
authors.initials: M
authors.lastname: Hung
authors.forename: Jeremy D
authors.initials: JD
authors.lastname: Franklin
authors.forename: Shirley D
authors.initials: SD
authors.lastname: Hon
authors.forename: Christine
authors.initials: C
authors.lastname: Cheng
authors.forename: Jillian
authors.initials: J
authors.lastname: Conrad
authors.forename: Charles L
authors.initials: CL
authors.lastname: Saltzman
mesh_terms: D016512:Ankle Injuries / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D004185:Disability Evaluation; D005528:Foot / Q000503:physiopathology; D018409:Foot Injuries / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D006305:Health Status Indicators; D006801:Humans; D017063:Outcome Assessment, Health Care / Q000379:methods*; D011594:Psychometrics; D020127:Recovery of Function; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires
keywords: instrument; item response theory; orthopedics; patient-reported outcomes; psychometrics; reliability; validity